| Popis: |
Commencing in 1975, under the auspices of W.H.O., weekly applications of insecticides have been employed to control the blackfly which transmits human river blindness in West Africa. The results provided in this paper do not show, as a whole, any clear impact of OCP-applied pesticides on fish populations. The total catch, the number of species caught in each sample and coefficient of condition, appeared to fluctuate around a mean value, and no long-term drop was observed over the period investigated. The seasonal pattern is generally clear. In some cases longer term declines occur, generally being followed by a rise correlating with changing hydrological conditions. |
